Data centers are usually composed of various Internet Small Computer System Interface (iSCSI) and FibreChannel storage devices, and also even direct attached storage, such as a disk. Such storage devices are commonly known as physical volumes. All of this storage may be from different manufacturers and contain un-initialized data that was previously used by some machines. The physical volumes are generally combined into a volume group, which creates a pool of space out of, which LVs (LVs) are allocated. As such, the LVs also contain the un-initialized data, which is accessible to other machines, resulting in a security risk. As a result, it is necessary to erase the data in the LV in order to prevent access to the data by other machines.
One current technique for erasing un-initialized data on LVs is to overwrite each LV with zeros. LVs may be copied to new LVs or to existing LVs, which are then overwritten with zeros, effectively erasing all the data. However, this technique can take a long time depending on the amount of data stored on the LV.
Another technique for erasing un-initialized data on the LV is to use a sparse file or a snapshot of a virtual machine image. When a LV is created, a specific number of logical blocks are assigned to the LV. A table in the LV maps each of the logical blocks into physical blocks so that when a customer writes into the logical blocks, each of the logical blocks are allocated to the physical volume at a specific location. However, the logical blocks are not contiguously allocated, and reading such non-contiguous physical blocks is a slow process as the system needs to seek to a different location with each block read.